SQL Server的Descending Indexes

USE [test]
GO
 
 
CREATE TABLE [dbo].[tt8](
    [id] INT IDENTITY(1,1) NOT NULL,
    [win_num] [int] NOT NULL DEFAULT ((0)),
    [lost_num] [int] NOT NULL   DEFAULT ((0)),
    [draw_num] [int] NOT NULL  DEFAULT ((0)),
    [offline_num] [int] NOT NULL   DEFAULT ((0)),
    [login_key] [nvarchar](50) NULL
 CONSTRAINT [PK_user_T] PRIMARY KEY CLUSTERED 
(
    [id] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
) ON [PRIMARY]
 
GO

DECLARE @i INT;
DECLARE @sql NVARCHAR(MAX);
SET @i = 1;
WHILE @i <= 9999
    BEGIN
        SET @sql = 'INSERT  INTO [dbo].[tt8]
        ( 
          [win_num] ,
          [lost_num] ,
          [draw_num] ,
          [offline_num] ,
          [login_key] 
         
        )
VALUES  ( 
        ''' + CAST(@i AS NVARCHAR(3000)) + ''' ,
        ''' + CAST(@i AS NVARCHAR(3000)) + ''' ,
        ''' + CAST(@i AS NVARCHAR(3000)) + ''' ,
            ''' + CAST(@i AS NVARCHAR(3000)) + ''' ,
            ''' + CAST(@i AS NVARCHAR(3000)) + ''' 
        );';
        EXEC ( @sql );
        SET @i = @i + 1;
    END;

select top 10 * from [dbo].[tt8] order by  [draw_num] asc,[win_num] desc

CREATE NONCLUSTERED INDEX [IX_tt8_draw_numwin_num] ON [dbo].[tt8]
(
    [draw_num] ASC,
    [win_num] ASC
)WITH (online= ON) ON [PRIMARY]
GO

DROP INDEX [IX_tt8_draw_numwin_num]    ON [tt8]
 
CREATE NONCLUSTERED INDEX [IX_tt8_draw_numwin_num]   ON [dbo].[tt8]
(
    [draw_num] ASC ,
    [win_num] DESC 
)  WITH ( ONLINE = ON ) ON [PRIMARY]
GO

CREATE NONCLUSTERED INDEX [IX_tt8_draw_num]   ON [dbo].[tt8]
(
    [draw_num] ASC 
)  WITH ( ONLINE = ON ) ON [PRIMARY]
GO